Null/undefined return in WordPress AJAX request

I am not sure the output you have provided is the correct one but do you notice the ‘0’ character at the end of your string?

{"title":"R=3+","dates":["06\/04\/2014","11\/05\/2014","15\/06\/2014","27\/07\/2014","17\/08\/2014","28\/09\/2014","05\/10\/2014","19\/10\/2014","09\/11\/2014","23\/11\/2014","14\/12\/2014"],"series":[{"data":[[1396738800000,284],[1399762800000,350],[1402786800000,212],[1406415600000,296],[1408230000000,220],[1411858800000,253],[1412463600000,200],[1413673200000,310],[1415491200000,180],[1416700800000,156],[1418515200000,290]],"name":"Bulls"}]}0

That is enough to cause the JSON parser to fail.

Also, don’t use the contentType property like that since you don’t send any JSON, you should remove that line altogether.

Related Posts:

  1. JSON parsing error syntax error unexpected end of input
  2. jQuery Ajax error handling, show custom exception messages
  3. My javascript is returning this error: $.ajax is not a function
  4. Ajax TypeError: $.POST is not a function
  5. TypeError: $.ajax(…) is not a function?
  6. XML Parsing Error: not well-formed in FireFox but good in Chrome
  7. How to get a cross-origin resource sharing (CORS) post request working
  8. jQuery Form Validation before Ajax submit
  9. jQuery – Illegal invocation
  10. jQuery ajax error function
  11. ajax stopped working when not logged in?
  12. Using jQuery to delete data stored in wp_options
  13. AJAX nonce with check_ajax_referer()
  14. wp_mail script with jQuery post
  15. Ajax call does not activate callback function
  16. AJAX call returns 0
  17. jQuery and AJAX Not working with Select Form Element
  18. How to pass both action and formdata in wordpress ajax?
  19. jquery & ajax getting data to php in wordpress
  20. AJAX returns response 0
  21. Basic WordPress AJAX Call
  22. AJAX post into pop-up div
  23. Bind to WPSetAsThumbnail
  24. Appending anchor tag to next post
  25. How to load whole WordPress pages dynamically with AJAX/jQuery like this following website?
  26. Creating custom AJAX requests
  27. Registration e-mail check with AJAX
  28. Cannot access elements of json object
  29. Basic ajax call in WordPress
  30. Updating User Profile with AJAX not working
  31. Auto Load New Posts
  32. wp_ajax() question.. not using wp_enqueue_script?
  33. wp_ajax unauthenticated and authenticated
  34. Showing Author Information and Latest Post by author in lightbox when clicked on the name of the author
  35. WordPress ajax function parameter value not being passed
  36. Accept AJAX call with serialized form data
  37. WordPress customizer refresh screen after save
  38. Is there a restriction in WP on the use of jQuery load function?
  39. Ajax not posting form data to query in PHP function
  40. Front-end Ajax File Upload
  41. Display data on same page as form without refresh
  42. gravity forms jQuery.load into modal [closed]
  43. Ajaxify calendar
  44. Error when posting comment form: The error is TypeError: e[h] is not a function
  45. jQuery ajax call throws an HTTP 302
  46. Ajax, Permalinks and post_thumbnail
  47. WooCommerce Ajax Cart Update Stopped Working
  48. WordPress AJAX Load More function duplicating a post
  49. Advanced Ajax Page Loader (AAPL) blocks resources
  50. First Attempt at AJAX and it keeps getting Canceled. Can’t Get Results to Show
  51. Passing a varible from jQuery to PHP
  52. videopress videos are not displayed when loading the content with ajax in a lightbox
  53. Retrieve post info within AJAX helper function
  54. How to return multiple arguments from AJAX callback function
  55. Display posts from another site using REST API in an asynchronous manner
  56. Why use admin-ajax.php when loading pages through AJAX?
  57. WP Rest Api / Ajax POST not working when not logged in
  58. Why does my jQuery AJAX return 0?
  59. Simplest ajax form not working when it should
  60. Ajax Validation for reCaptcha
  61. Sorting WP Auctions by date/price?
  62. Loading dynamic content with AJAX breaking jQuery
  63. why is my wordpress Jquery-Ajax call not working?
  64. How to retrieve WP_Object that is inside an array of another array
  65. fill form fields with ajax response
  66. Adding custom cart price with Ajax in wordpress
  67. Can’t add classes using jQuery from a JSON string with get_body_class()
  68. Ajax call through admin-ajax.php returns 404 error
  69. WordPress Insert not working with ajax
  70. Search query with Ajax
  71. WP AJAX API with JS file
  72. admin ajax php success returns 0
  73. Why is ajax working on one server and not the next?
  74. Is there some jQuery conflict here?
  75. How to use wp_update_post with ajax on frontend
  76. Getting jQuery AJAX to work in WordPress (getting -1)
  77. Connect Agile Carousel to WordPress AJAX
  78. AJAX calendar navigation returns -1
  79. Which hook to use when adding ajax to viewer-facing side?
  80. my example with ajax doesn’t work
  81. jQuery forms & updating info
  82. Orderby post__in Not Working Correctly?
  83. jQuery.post() calling function with parameter
  84. $_POST empty in using new php file added to theme
  85. Passing variable data from external jQuery file to options.php
  86. Retrieve customizer value using ajax or customizer api and print the value in theme
  87. Displaying contents of a tab
  88. owl carousel not working after ajax load [duplicate]
  89. WordPress version for this autocomplete jQuery code
  90. Ajax autocomplete based on usercode
  91. Variable not being returned from Ajax Javascript (though javascript receives it)
  92. jQuery AJAX add json2 dependency?
  93. How to respond with WP_Ajax_Response();
  94. How to pass more information though separate post keys via AJAX
  95. Loop not appending through infinite-scroll ajax call
  96. Get selected value with PHP and jQuery
  97. How to combine jQuery in-place editor with $wpdb->update
  98. Load loop images on click / defer image loading until click or other event
  99. Widget won’t work due to old JavaScript? Any ideas how to make it work? [closed]
  100. Contact Form 7 – Submit Form not working After Ajax Request [closed]